Many conventional incandescent light bulbs utilize a so-called Edison base or cap. FIG. 16 shows a conventional light bulb 50 with an Edison base 20 having a conductive metal structure 24 with an upper portion of generally cylindrical shape that tapers to a bottom portion having a contact tip 22 and an insulative intermediate structure 26. A Tungsten filament (not shown) is mounted within a glass bulb 52 that is attached to the Edison base 20, with first and second wires (not shown) connected from the filament to the threaded structure 24 and to the tip contact 22, respectively. In use, the bulb assembly 50 is screwed into a corresponding socket of a light fixture (not shown) in which the contact 22 is electrically connected with a first power line and the threaded conductor 24 engages with conductive mating threads for electrical connection to a second power line. The socket provides AC current to the filament through these connections to cause light emission from the filament. Other popular lamp base styles include bayonet bases with two lug contacts extending outwardly from the cylindrical base structure for push and twist connection to a socket with corresponding L-shaped slots, as well as bases having two pin or lug type contacts extending from the bottom of the base or cap. Each lamp base or cap type typically comes in a variety of sizes and are commonly designated by a diameter dimension such as 27 mm Edison types (E27), 22 mm Bayonet types (B22), etc.
In recent years, the inefficiencies of conventional incandescent bulbs 50 has lead to development of compact fluorescent lamps (CFLs), halogen lamps, LED array lighting devices, and other more efficient forms of light sources. FIG. 16 shows a CFL 10 with a fluorescent lamp structure 14 mounted to an Edison base 20 via an intermediate housing 12 which includes power conversion circuitry, such as a rectifier, DC-DC converter, and an inverter to provide high frequency AC power to the lamp 14. Replacement of incandescent light bulbs 50 with CFLs or LED light sources in existing fixtures can reduce electrical energy consumption, where the provision of an Edison base 20 in such replacement CFLs 10 allows simple changeout of incandescent bulbs 50 with a CFL 10 without having to install a different fixture socket. However, the replacement CFL 10 is typically taller than the bulb 50 it is replacing. For example, FIG. 16 shows a typical height difference 16, with the CFL device 10 being approximately 20% taller than the incandescent bulb 10. This physical size difference creates compatibility issues with the type and size of fixtures where CFLs and other replacement light sources can be used.